xamarinmac 
namespace System.Net.Http.Formatting
{
    public abstract class MediaTypeFormatter : Object
    {
        public Collection<MediaTypeMapping> MediaTypeMappings { get; }
    }
}
.NET
5.06.07.08.09.010.011.0
.NET Core
1.01.12.02.12.23.03.1
.NET Framework
4.54.5.14.5.24.64.6.14.6.24.74.7.14.7.24.84.8.1
.NET Standard
1.31.41.51.62.02.1
Information specific to xamarinmac
Assembly

System.Net.Http.Formatting , Version=6.0.0.0, PublicKeyToken=31bf3856ad364e35

Referencing

Your project needs a package reference to Microsoft.AspNet.WebApi.Client.

Package Microsoft.AspNet.WebApi.Client (6.0.0) netstandard2.0
Platform Restrictions

This framework does not have platform annotations.

  • Built-in API
  • Package-provided API